/*
 * Copyright (C) 2006 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

/*
 * Class taken from the stock browser in AOSP.
 * Only slightly modified to meet Tint's needs.
 */

package com.mogoweb.ui.views;

import android.content.Context;
import android.graphics.PointF;
import android.graphics.Rect;
import android.util.AttributeSet;
import android.view.FocusFinder;
import android.view.InputDevice;
import android.view.KeyEvent;
import android.view.MotionEvent;
import android.view.VelocityTracker;
import android.view.View;
import android.view.ViewConfiguration;
import android.view.ViewDebug;
import android.view.ViewGroup;
import android.view.ViewParent;
import android.view.accessibility.AccessibilityEvent;
import android.view.accessibility.AccessibilityNodeInfo;
import android.view.animation.AnimationUtils;
import android.widget.FrameLayout;
import android.widget.LinearLayout;
import android.widget.OverScroller;
import android.widget.TextView;

import java.util.List;

/**
 * Layout container for a view hierarchy that can be scrolled by the user,
 * allowing it to be larger than the physical display.  A ScrollView
 * is a {@link FrameLayout}, meaning you should place one child in it
 * containing the entire contents to scroll; this child may itself be a layout
 * manager with a complex hierarchy of objects.  A child that is often used
 * is a {@link LinearLayout} in a vertical orientation, presenting a vertical
 * array of top-level items that the user can scroll through.
 *
 * <p>The {@link TextView} class also
 * takes care of its own scrolling, so does not require a ScrollView, but
 * using the two together is possible to achieve the effect of a text view
 * within a larger container.
 *
 * <p>ScrollView only supports vertical scrolling.
 *
 * @attr ref android.R.styleable#ScrollView_fillViewport
 */
public class ScrollerView extends FrameLayout {
	static final int ANIMATED_SCROLL_GAP = 250;

	static final float MAX_SCROLL_FACTOR = 0.5f;

	private long mLastScroll;

	private final Rect mTempRect = new Rect();
	protected OverScroller mScroller;

	/**
	 * Position of the last motion event.
	 */
	private float mLastMotionY;

	/**
	 * True when the layout has changed but the traversal has not come through yet.
	 * Ideally the view hierarchy would keep track of this for us.
	 */
	private boolean mIsLayoutDirty = true;

	/**
	 * The child to give focus to in the event that a child has requested focus while the
	 * layout is dirty. This prevents the scroll from being wrong if the child has not been
	 * laid out before requesting focus.
	 */
	protected View mChildToScrollTo = null;

	/**
	 * True if the user is currently dragging this ScrollView around. This is
	 * not the same as 'is being flinged', which can be checked by
	 * mScroller.isFinished() (flinging begins when the user lifts his finger).
	 */
	protected boolean mIsBeingDragged = false;

	/**
	 * Determines speed during touch scrolling
	 */
	private VelocityTracker mVelocityTracker;

	/**
	 * When set to true, the scroll view measure its child to make it fill the currently
	 * visible area.
	 */
	@ViewDebug.ExportedProperty(category = "layout")
	private boolean mFillViewport;

	/**
	 * Whether arrow scrolling is animated.
	 */
	private boolean mSmoothScrollingEnabled = true;

	private int mTouchSlop;
	protected int mMinimumVelocity;
	private int mMaximumVelocity;

	private int mOverscrollDistance;
	private int mOverflingDistance;

	/**
	 * ID of the active pointer. This is used to retain consistency during
	 * drags/flings if multiple pointers are used.
	 */
	private int mActivePointerId = INVALID_POINTER;

	/**
	 * The StrictMode "critical time span" objects to catch animation
	 * stutters.  Non-null when a time-sensitive animation is
	 * in-flight.  Must call finish() on them when done animating.
	 * These are no-ops on user builds.
	 */
	private Span mScrollStrictSpan = null;  // aka "drag"
	private Span mFlingStrictSpan = null;

	/**
	 * Sentinel value for no current active pointer.
	 * Used by {@link #mActivePointerId}.
	 */
	private static final int INVALID_POINTER = -1;

	/**
	 * orientation of the scrollview
	 */
	protected boolean mHorizontal;

	protected boolean mIsOrthoDragged;
	private float mLastOrthoCoord;
	private View mDownView;
	private PointF mDownCoords;

	private float mScrollFactor;

	public ScrollerView(Context context) {
		this(context, null);
	}

	public ScrollerView(Context context, AttributeSet attrs) {
		this(context, attrs, 0);
	}

	public ScrollerView(Context context, AttributeSet attrs, int defStyle) {
		super(context, attrs, defStyle);
		initScrollView();
		setFillViewport(true);
	}

	private void initScrollView() {
		mScroller = new OverScroller(getContext());
		setFocusable(true);
		setDescendantFocusability(FOCUS_AFTER_DESCENDANTS);
		setWillNotDraw(false);
		final ViewConfiguration configuration = ViewConfiguration.get(getContext());
		mTouchSlop = configuration.getScaledTouchSlop();
		mMinimumVelocity = configuration.getScaledMinimumFlingVelocity();
		mMaximumVelocity = configuration.getScaledMaximumFlingVelocity();
		mOverscrollDistance = configuration.getScaledOverscrollDistance();
		mOverflingDistance = configuration.getScaledOverflingDistance();
		mDownCoords = new PointF();

		mScrollFactor = 64 * getContext().getResources().getDisplayMetrics().density + 0.5f;
	}

	public void setOrientation(int orientation) {
		mHorizontal = (orientation == LinearLayout.HORIZONTAL);
		requestLayout();
	}

	@Override
	public boolean shouldDelayChildPressedState() {
		return true;
	}

	@Override
	protected float getTopFadingEdgeStrength() {
		if (getChildCount() == 0) {
			return 0.0f;
		}
		if (mHorizontal) {
			final int length = getHorizontalFadingEdgeLength();
			if (getScrollX() < length) {
				return getScrollX() / (float) length;
			}
		} else {
			final int length = getVerticalFadingEdgeLength();
			if (getScrollY() < length) {
				return getScrollY() / (float) length;
			}
		}
		return 1.0f;
	}

	@Override
	protected float getBottomFadingEdgeStrength() {
		if (getChildCount() == 0) {
			return 0.0f;
		}
		if (mHorizontal) {
			final int length = getHorizontalFadingEdgeLength();
			final int bottomEdge = getWidth() - getPaddingRight();
			final int span = getChildAt(0).getRight() - getScrollX() - bottomEdge;
			if (span < length) {
				return span / (float) length;
			}
		} else {
			final int length = getVerticalFadingEdgeLength();
			final int bottomEdge = getHeight() - getPaddingBottom();
			final int span = getChildAt(0).getBottom() - getScrollY() - bottomEdge;
			if (span < length) {
				return span / (float) length;
			}
		}
		return 1.0f;
	}

	/**
	 * @return The maximum amount this scroll view will scroll in response to
	 *   an arrow event.
	 */
	public int getMaxScrollAmount() {
		return (int) (MAX_SCROLL_FACTOR * (mHorizontal
				? (getRight() - getLeft()) : (getBottom() - getTop())));
	}


	@Override
	public void addView(View child) {
		if (getChildCount() > 0) {
			throw new IllegalStateException("ScrollView can host only one direct child");
		}

		super.addView(child);
	}

	@Override
	public void addView(View child, int index) {
		if (getChildCount() > 0) {
			throw new IllegalStateException("ScrollView can host only one direct child");
		}

		super.addView(child, index);
	}

	@Override
	public void addView(View child, ViewGroup.LayoutParams params) {
		if (getChildCount() > 0) {
			throw new IllegalStateException("ScrollView can host only one direct child");
		}

		super.addView(child, params);
	}

	@Override
	public void addView(View child, int index, ViewGroup.LayoutParams params) {
		if (getChildCount() > 0) {
			throw new IllegalStateException("ScrollView can host only one direct child");
		}

		super.addView(child, index, params);
	}

	/**
	 * @return Returns true this ScrollView can be scrolled
	 */
	private boolean canScroll() {
		View child = getChildAt(0);
		if (child != null) {
			if (mHorizontal) {
				return getWidth() < child.getWidth() + getPaddingLeft() + getPaddingRight();
			} else {
				return getHeight() < child.getHeight() + getPaddingTop() + getPaddingBottom();
			}
		}
		return false;
	}

	/**
	 * Indicates whether this ScrollView's content is stretched to fill the viewport.
	 *
	 * @return True if the content fills the viewport, false otherwise.
	 *
	 * @attr ref android.R.styleable#ScrollView_fillViewport
	 */
	public boolean isFillViewport() {
		return mFillViewport;
	}

	/**
	 * Indicates this ScrollView whether it should stretch its content height to fill
	 * the viewport or not.
	 *
	 * @param fillViewport True to stretch the content's height to the viewport's
	 *        boundaries, false otherwise.
	 *
	 * @attr ref android.R.styleable#ScrollView_fillViewport
	 */
	public void setFillViewport(boolean fillViewport) {
		if (fillViewport != mFillViewport) {
			mFillViewport = fillViewport;
			requestLayout();
		}
	}

	/**
	 * @return Whether arrow scrolling will animate its transition.
	 */
	public boolean isSmoothScrollingEnabled() {
		return mSmoothScrollingEnabled;
	}

	/**
	 * Set whether arrow scrolling will animate its transition.
	 * @param smoothScrollingEnabled whether arrow scrolling will animate its transition
	 */
	public void setSmoothScrollingEnabled(boolean smoothScrollingEnabled) {
		mSmoothScrollingEnabled = smoothScrollingEnabled;
	}

	@Override
	protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
		super.onMeasure(widthMeasureSpec, heightMeasureSpec);

		if (!mFillViewport) {
			return;
		}

		final int heightMode = MeasureSpec.getMode(heightMeasureSpec);
		if (heightMode == MeasureSpec.UNSPECIFIED) {
			return;
		}

		if (getChildCount() > 0) {
			final View child = getChildAt(0);
			if (mHorizontal) {
				int width = getMeasuredWidth();
				if (child.getMeasuredWidth() < width) {
					final FrameLayout.LayoutParams lp = (LayoutParams) child
							.getLayoutParams();

					int childHeightMeasureSpec = getChildMeasureSpec(
							heightMeasureSpec, getPaddingTop() + getPaddingBottom(),
							lp.height);
					width -= getPaddingLeft();
					width -= getPaddingRight();
					int childWidthMeasureSpec = MeasureSpec.makeMeasureSpec(
							width, MeasureSpec.EXACTLY);

					child.measure(childWidthMeasureSpec, childHeightMeasureSpec);
				}
			} else {
				int height = getMeasuredHeight();
				if (child.getMeasuredHeight() < height) {
					final FrameLayout.LayoutParams lp = (LayoutParams) child
							.getLayoutParams();

					int childWidthMeasureSpec = getChildMeasureSpec(
							widthMeasureSpec, getPaddingLeft() + getPaddingRight(),
							lp.width);
					height -= getPaddingTop();
					height -= getPaddingBottom();
					int childHeightMeasureSpec = MeasureSpec.makeMeasureSpec(
							height, MeasureSpec.EXACTLY);

					child.measure(childWidthMeasureSpec, childHeightMeasureSpec);
				}
			}
		}
	}

	@Override
	public boolean dispatchKeyEvent(KeyEvent event) {
		// Let the focused view and/or our descendants get the key first
		return super.dispatchKeyEvent(event) || executeKeyEvent(event);
	}

	/**
	 * You can call this function yourself to have the scroll view perform
	 * scrolling from a key event, just as if the event had been dispatched to
	 * it by the view hierarchy.
	 *
	 * @param event The key event to execute.
	 * @return Return true if the event was handled, else false.
	 */
	public boolean executeKeyEvent(KeyEvent event) {
		mTempRect.setEmpty();

		if (!canScroll()) {
			if (isFocused() && event.getKeyCode() != KeyEvent.KEYCODE_BACK) {
				View currentFocused = findFocus();
				if (currentFocused == this) currentFocused = null;
				View nextFocused = FocusFinder.getInstance().findNextFocus(this,
						currentFocused, View.FOCUS_DOWN);
				return nextFocused != null
						&& nextFocused != this
						&& nextFocused.requestFocus(View.FOCUS_DOWN);
			}
			return false;
		}

		boolean handled = false;
		if (event.getAction() == KeyEvent.ACTION_DOWN) {
			switch (event.getKeyCode()) {
			case KeyEvent.KEYCODE_DPAD_UP:
				if (!event.isAltPressed()) {
					handled = arrowScroll(View.FOCUS_UP);
				} else {
					handled = fullScroll(View.FOCUS_UP);
				}
				break;
			case KeyEvent.KEYCODE_DPAD_DOWN:
				if (!event.isAltPressed()) {
					handled = arrowScroll(View.FOCUS_DOWN);
				} else {
					handled = fullScroll(View.FOCUS_DOWN);
				}
				break;
			case KeyEvent.KEYCODE_SPACE:
				pageScroll(event.isShiftPressed() ? View.FOCUS_UP : View.FOCUS_DOWN);
				break;
			}
		}

		return handled;
	}

	private boolean inChild(int x, int y) {
		if (getChildCount() > 0) {
			final int scrollY = getScrollY();
			final View child = getChildAt(0);
			return !(y < child.getTop() - scrollY
					|| y >= child.getBottom() - scrollY
					|| x < child.getLeft()
					|| x >= child.getRight());
		}
		return false;
	}

	private void initOrResetVelocityTracker() {
		if (mVelocityTracker == null) {
			mVelocityTracker = VelocityTracker.obtain();
		} else {
			mVelocityTracker.clear();
		}
	}

	private void initVelocityTrackerIfNotExists() {
		if (mVelocityTracker == null) {
			mVelocityTracker = VelocityTracker.obtain();
		}
	}

	private void recycleVelocityTracker() {
		if (mVelocityTracker != null) {
			mVelocityTracker.recycle();
			mVelocityTracker = null;
		}
	}

	@Override
	public void requestDisallowInterceptTouchEvent(boolean disallowIntercept) {
		if (disallowIntercept) {
			recycleVelocityTracker();
		}
		super.requestDisallowInterceptTouchEvent(disallowIntercept);
	}

	@Override
	public boolean onInterceptTouchEvent(MotionEvent ev) {
		/*
		 * This method JUST determines whether we want to intercept the motion.
		 * If we return true, onMotionEvent will be called and we do the actual
		 * scrolling there.
		 */

		/*
		 * Shortcut the most recurring case: the user is in the dragging state
		 * and he is moving his finger. We want to intercept this motion.
		 */
		final int action = ev.getAction();
		
		if ((action == MotionEvent.ACTION_MOVE) && (mIsBeingDragged)) {
			return true;
		}
		if ((action == MotionEvent.ACTION_MOVE) && (mIsOrthoDragged)) {
			return true;
		}
		switch (action & MotionEvent.ACTION_MASK) {
		case MotionEvent.ACTION_MOVE: {
			/*
			 * mIsBeingDragged == false, otherwise the shortcut would have
			 * caught it. Check whether the user has moved far enough from his
			 * original down touch.
			 */

			/*
			 * Locally do absolute value. mLastMotionY is set to the y value of
			 * the down event.
			 */
			final int activePointerId = mActivePointerId;
			if (activePointerId == INVALID_POINTER) {
				// If we don't have a valid id, the touch down wasn't on
				// content.
				break;
			}

			final int pointerIndex = ev.findPointerIndex(activePointerId);
			final float y = mHorizontal ? ev.getX(pointerIndex) : ev
					.getY(pointerIndex);
			final int yDiff = (int) Math.abs(y - mLastMotionY);
			if (yDiff > mTouchSlop) {
				mIsBeingDragged = true;
				mLastMotionY = y;
				initVelocityTrackerIfNotExists();
				mVelocityTracker.addMovement(ev);
				if (mScrollStrictSpan == null) {
					mScrollStrictSpan = enterCriticalSpan("ScrollView-scroll");
				}
			} else {
				final float ocoord = mHorizontal ? ev.getY(pointerIndex) : ev
						.getX(pointerIndex);
				if (Math.abs(ocoord - mLastOrthoCoord) > mTouchSlop) {
					mIsOrthoDragged = true;
					mLastOrthoCoord = ocoord;
					initVelocityTrackerIfNotExists();
					mVelocityTracker.addMovement(ev);
				}
			}
			break;
		}

		case MotionEvent.ACTION_DOWN: {
			final float y = mHorizontal ? ev.getX() : ev.getY();
			mDownCoords.x = ev.getX();
			mDownCoords.y = ev.getY();
			if (!inChild((int) ev.getX(), (int) ev.getY())) {
				mIsBeingDragged = false;
				recycleVelocityTracker();
				break;
			}

			/*
			 * Remember location of down touch. ACTION_DOWN always refers to
			 * pointer index 0.
			 */
			mLastMotionY = y;
			mActivePointerId = ev.getPointerId(0);

			initOrResetVelocityTracker();
			mVelocityTracker.addMovement(ev);
			/*
			 * If being flinged and user touches the screen, initiate drag;
			 * otherwise don't. mScroller.isFinished should be false when being
			 * flinged.
			 */
			mIsBeingDragged = !mScroller.isFinished();
			if (mIsBeingDragged && mScrollStrictSpan == null) {
				mScrollStrictSpan = enterCriticalSpan("ScrollView-scroll");
			}
			mIsOrthoDragged = false;
			final float ocoord = mHorizontal ? ev.getY() : ev.getX();
			mLastOrthoCoord = ocoord;
			mDownView = findViewAt((int) ev.getX(), (int) ev.getY());
			
			break;
		}

		case MotionEvent.ACTION_CANCEL:
		case MotionEvent.ACTION_UP:
			/* Release the drag */
			mIsBeingDragged = false;
			mIsOrthoDragged = false;
			mActivePointerId = INVALID_POINTER;
			recycleVelocityTracker();
			if (mScroller.springBack(getScrollX(), getScrollY(), 0, 0, 0,
					getScrollRange())) {
				invalidate();
			}
			break;
		case MotionEvent.ACTION_POINTER_UP:
			onSecondaryPointerUp(ev);
			break;
		}

		/*
		 * The only time we want to intercept motion events is if we are in the
		 * drag mode.
		 */
		return mIsBeingDragged || mIsOrthoDragged;
	}

	@Override
	public boolean onTouchEvent(MotionEvent ev) {
		initVelocityTrackerIfNotExists();
		mVelocityTracker.addMovement(ev);

		final int action = ev.getAction();
		switch (action & MotionEvent.ACTION_MASK) {
		case MotionEvent.ACTION_DOWN: {
			mIsBeingDragged = getChildCount() != 0;
			if (!mIsBeingDragged) {
				return false;
			}

			/*
			 * If being flinged and user touches, stop the fling. isFinished
			 * will be false if being flinged.
			 */
			if (!mScroller.isFinished()) {
				mScroller.abortAnimation();
				if (mFlingStrictSpan != null) {
					mFlingStrictSpan.finish();
					mFlingStrictSpan = null;
				}
			}

			// Remember where the motion event started
			mLastMotionY = mHorizontal ? ev.getX() : ev.getY();
			mActivePointerId = ev.getPointerId(0);
			break;
		}
		case MotionEvent.ACTION_MOVE:
			
			final int activePointerIndex = ev.findPointerIndex(mActivePointerId);
			final float x = ev.getX(activePointerIndex);
			float y = ev.getY(activePointerIndex);
			
//			if (mIsOrthoDragged) {
			if (isOrthoMove(x - mDownCoords.x, y - mDownCoords.y)) {
				mIsOrthoDragged = true;
				// Scroll to follow the motion event
//				final int activePointerIndex = ev.findPointerIndex(mActivePointerId);
//				final float x = ev.getX(activePointerIndex);
//				final float y = ev.getY(activePointerIndex);
//				if (isOrthoMove(x - mDownCoords.x, y - mDownCoords.y)) {
					onOrthoDrag(mDownView, mHorizontal
							? y - mDownCoords.y
									: x - mDownCoords.x);
//				}
			} else if (mIsBeingDragged) {
				// Scroll to follow the motion event
//				final int activePointerIndex = ev.findPointerIndex(mActivePointerId);
//				final float y = mHorizontal ? ev.getX(activePointerIndex) : ev.getY(activePointerIndex);
				y = mHorizontal ? ev.getX(activePointerIndex) : ev.getY(activePointerIndex);
				final int deltaY = (int) (mLastMotionY - y);
				mLastMotionY = y;

				final int oldX = getScrollX();
				final int oldY = getScrollY();
				final int range = getScrollRange();
				if (mHorizontal) {
					if (overScrollBy(deltaY, 0, getScrollX(), 0, range, 0,
							mOverscrollDistance, 0, true)) {
						// Break our velocity if we hit a scroll barrier.
						mVelocityTracker.clear();
					}
				} else {
					if (overScrollBy(0, deltaY, 0, getScrollY(), 0, range,
							0, mOverscrollDistance, true)) {
						// Break our velocity if we hit a scroll barrier.
						mVelocityTracker.clear();
					}
				}
				onScrollChanged(getScrollX(), getScrollY(), oldX, oldY);

				final int overscrollMode = getOverScrollMode();
				if (overscrollMode == OVER_SCROLL_ALWAYS ||
						(overscrollMode == OVER_SCROLL_IF_CONTENT_SCROLLS && range > 0)) {
					final int pulledToY = mHorizontal ? oldX + deltaY : oldY + deltaY;
					if (pulledToY < 0) {
						onPull(pulledToY);
					} else if (pulledToY > range) {
						onPull(pulledToY - range);
					} else {
						onPull(0);
					}
				}
			}
			break;
		case MotionEvent.ACTION_UP:
			final VelocityTracker vtracker = mVelocityTracker;
			vtracker.computeCurrentVelocity(1000, mMaximumVelocity);
			if (isOrthoMove(vtracker.getXVelocity(mActivePointerId),
					vtracker.getYVelocity(mActivePointerId))
					&& mMinimumVelocity < Math.abs((mHorizontal ? vtracker.getYVelocity()
							: vtracker.getXVelocity()))) {
				onOrthoFling(mDownView, mHorizontal ? vtracker.getYVelocity()
						: vtracker.getXVelocity());
				break;
			}
			if (mIsOrthoDragged) {
				onOrthoDragFinished(mDownView);
				mActivePointerId = INVALID_POINTER;
				endDrag();
			} else if (mIsBeingDragged) {
				final VelocityTracker velocityTracker = mVelocityTracker;
				velocityTracker.computeCurrentVelocity(1000, mMaximumVelocity);
				int initialVelocity = mHorizontal
						? (int) velocityTracker.getXVelocity(mActivePointerId)
								: (int) velocityTracker.getYVelocity(mActivePointerId);

						if (getChildCount() > 0) {
							if ((Math.abs(initialVelocity) > mMinimumVelocity)) {
								fling(-initialVelocity);
							} else {
								final int bottom = getScrollRange();
								if (mHorizontal) {
									if (mScroller.springBack(getScrollX(), getScrollY(), 0, bottom, 0, 0)) {
										invalidate();
									}
								} else {
									if (mScroller.springBack(getScrollX(), getScrollY(), 0, 0, 0, bottom)) {
										invalidate();
									}
								}
							}
							onPull(0);
						}

						mActivePointerId = INVALID_POINTER;
						endDrag();
			}
			break;
		case MotionEvent.ACTION_CANCEL:
			if (mIsOrthoDragged) {
				onOrthoDragFinished(mDownView);
				mActivePointerId = INVALID_POINTER;
				endDrag();
			} else if (mIsBeingDragged && getChildCount() > 0) {
				if (mHorizontal) {
					if (mScroller.springBack(getScrollX(), getScrollY(), 0, getScrollRange(), 0, 0)) {
						invalidate();
					}
				} else {
					if (mScroller.springBack(getScrollX(), getScrollY(), 0, 0, 0, getScrollRange())) {
						invalidate();
					}
				}
				mActivePointerId = INVALID_POINTER;
				endDrag();
			}
			break;
		case MotionEvent.ACTION_POINTER_DOWN: {
			final int index = ev.getActionIndex();
//			final float y = mHorizontal ? ev.getX(index) : ev.getY(index);
			y = mHorizontal ? ev.getX(index) : ev.getY(index);
			mLastMotionY = y;
			mLastOrthoCoord = mHorizontal ? ev.getY(index) : ev.getX(index);
			mActivePointerId = ev.getPointerId(index);
			break;
		}
		case MotionEvent.ACTION_POINTER_UP:
			onSecondaryPointerUp(ev);
			mLastMotionY = mHorizontal
					? ev.getX(ev.findPointerIndex(mActivePointerId))
							: ev.getY(ev.findPointerIndex(mActivePointerId));
					break;
		}
		return true;
	}

	protected View findViewAt(int x, int y) {
		// subclass responsibility
		return null;
	}

	protected void onPull(int delta) {
	}

	private void onSecondaryPointerUp(MotionEvent ev) {
		final int pointerIndex = (ev.getAction() & MotionEvent.ACTION_POINTER_INDEX_MASK) >>
		MotionEvent.ACTION_POINTER_INDEX_SHIFT;
		final int pointerId = ev.getPointerId(pointerIndex);
		if (pointerId == mActivePointerId) {
			// This was our active pointer going up. Choose a new
			// active pointer and adjust accordingly.
			// TODO: Make this decision more intelligent.
			final int newPointerIndex = pointerIndex == 0 ? 1 : 0;
			mLastMotionY = mHorizontal ? ev.getX(newPointerIndex) : ev.getY(newPointerIndex);
			mActivePointerId = ev.getPointerId(newPointerIndex);
			if (mVelocityTracker != null) {
				mVelocityTracker.clear();
			}
			mLastOrthoCoord = mHorizontal ? ev.getY(newPointerIndex)
					: ev.getX(newPointerIndex);
		}
	}

	@Override
	public boolean onGenericMotionEvent(MotionEvent event) {
		if ((event.getSource() & InputDevice.SOURCE_CLASS_POINTER) != 0) {
			switch (event.getAction()) {
			case MotionEvent.ACTION_SCROLL: {
				if (!mIsBeingDragged) {
					if (mHorizontal) {
						final float hscroll = event
								.getAxisValue(MotionEvent.AXIS_HSCROLL);
						if (hscroll != 0) {
							final int delta = (int) (hscroll * mScrollFactor);	//getHorizontalScrollFactor()
							final int range = getScrollRange();
							int oldScrollX = getScrollX();
							int newScrollX = oldScrollX - delta;
							if (newScrollX < 0) {
								newScrollX = 0;
							} else if (newScrollX > range) {
								newScrollX = range;
							}
							if (newScrollX != oldScrollX) {
								super.scrollTo(newScrollX, getScrollY());
								return true;
							}
						}
					} else {
						final float vscroll = event
								.getAxisValue(MotionEvent.AXIS_VSCROLL);
						if (vscroll != 0) {
							final int delta = (int) (vscroll * mScrollFactor);	//getVerticalScrollFactor()
							final int range = getScrollRange();
							int oldScrollY = getScrollY();
							int newScrollY = oldScrollY - delta;
							if (newScrollY < 0) {
								newScrollY = 0;
							} else if (newScrollY > range) {
								newScrollY = range;
							}
							if (newScrollY != oldScrollY) {
								super.scrollTo(getScrollX(), newScrollY);
								return true;
							}
						}
					}
				}
			}
			}
		}
		return super.onGenericMotionEvent(event);
	}

	protected void onOrthoDrag(View draggedView, float distance) {
	}

	protected void onOrthoDragFinished(View draggedView) {
	}

	protected void onOrthoFling(View draggedView, float velocity) {
	}

	@Override
	protected void onOverScrolled(int scrollX, int scrollY,
			boolean clampedX, boolean clampedY) {
		// Treat animating scrolls differently; see #computeScroll() for why.
		if (!mScroller.isFinished()) {
			setScrollX(scrollX);
			setScrollY(scrollY);
			invalidateParentIfNeeded();
			if (mHorizontal && clampedX) {
				mScroller.springBack(getScrollX(), getScrollY(), 0, getScrollRange(), 0, 0);
			} else if (!mHorizontal && clampedY) {
				mScroller.springBack(getScrollX(), getScrollY(), 0, 0, 0, getScrollRange());
			}
		} else {
			super.scrollTo(scrollX, scrollY);
		}
		awakenScrollBars();
	}

	@Override
	public void onInitializeAccessibilityNodeInfo(AccessibilityNodeInfo info) {
		super.onInitializeAccessibilityNodeInfo(info);
		info.setScrollable(true);
	}

	@Override
	public void onInitializeAccessibilityEvent(AccessibilityEvent event) {
		super.onInitializeAccessibilityEvent(event);
		event.setScrollable(true);
	}

	@Override
	public boolean dispatchPopulateAccessibilityEvent(AccessibilityEvent event) {
		// Do not append text content to scroll events they are fired frequently
		// and the client has already received another event type with the text.
		if (event.getEventType() != AccessibilityEvent.TYPE_VIEW_SCROLLED) {
			super.dispatchPopulateAccessibilityEvent(event);
		}
		return false;
	}

	private int getScrollRange() {
		int scrollRange = 0;
		if (getChildCount() > 0) {
			View child = getChildAt(0);
			if (mHorizontal) {
				scrollRange = Math.max(0,
						child.getWidth() - (getWidth() - getPaddingRight() - getPaddingLeft()));
			} else {
				scrollRange = Math.max(0,
						child.getHeight() - (getHeight() - getPaddingBottom() - getPaddingTop()));
			}
		}
		return scrollRange;
	}

	/**
	 * <p>
	 * Finds the next focusable component that fits in the specified bounds.
	 * </p>
	 *
	 * @param topFocus look for a candidate is the one at the top of the bounds
	 *                 if topFocus is true, or at the bottom of the bounds if topFocus is
	 *                 false
	 * @param top      the top offset of the bounds in which a focusable must be
	 *                 found
	 * @param bottom   the bottom offset of the bounds in which a focusable must
	 *                 be found
	 * @return the next focusable component in the bounds or null if none can
	 *         be found
	 */
	private View findFocusableViewInBounds(boolean topFocus, int top, int bottom) {

		List<View> focusables = getFocusables(View.FOCUS_FORWARD);
		View focusCandidate = null;

		/*
		 * A fully contained focusable is one where its top is below the bound's
		 * top, and its bottom is above the bound's bottom. A partially
		 * contained focusable is one where some part of it is within the
		 * bounds, but it also has some part that is not within bounds.  A fully contained
		 * focusable is preferred to a partially contained focusable.
		 */
		boolean foundFullyContainedFocusable = false;

		int count = focusables.size();
		for (int i = 0; i < count; i++) {
			View view = focusables.get(i);
			int viewTop = mHorizontal ? view.getLeft() : view.getTop();
			int viewBottom = mHorizontal ? view.getRight() : view.getBottom();

			if (top < viewBottom && viewTop < bottom) {
				/*
				 * the focusable is in the target area, it is a candidate for
				 * focusing
				 */

				final boolean viewIsFullyContained = (top < viewTop) &&
						(viewBottom < bottom);

				if (focusCandidate == null) {
					/* No candidate, take this one */
					focusCandidate = view;
					foundFullyContainedFocusable = viewIsFullyContained;
				} else {
					final int ctop = mHorizontal ? focusCandidate.getLeft() : focusCandidate.getTop();
					final int cbot = mHorizontal ? focusCandidate.getRight() : focusCandidate.getBottom();
					final boolean viewIsCloserToBoundary =
							(topFocus && viewTop < ctop) ||
							(!topFocus && viewBottom > cbot);

					if (foundFullyContainedFocusable) {
						if (viewIsFullyContained && viewIsCloserToBoundary) {
							/*
							 * We're dealing with only fully contained views, so
							 * it has to be closer to the boundary to beat our
							 * candidate
							 */
							focusCandidate = view;
						}
					} else {
						if (viewIsFullyContained) {
							/* Any fully contained view beats a partially contained view */
							focusCandidate = view;
							foundFullyContainedFocusable = true;
						} else if (viewIsCloserToBoundary) {
							/*
							 * Partially contained view beats another partially
							 * contained view if it's closer
							 */
							focusCandidate = view;
						}
					}
				}
			}
		}

		return focusCandidate;
	}

	// i was here

	/**
	 * <p>Handles scrolling in response to a "page up/down" shortcut press. This
	 * method will scroll the view by one page up or down and give the focus
	 * to the topmost/bottommost component in the new visible area. If no
	 * component is a good candidate for focus, this scrollview reclaims the
	 * focus.</p>
	 *
	 * @param direction the scroll direction: {@link android.view.View#FOCUS_UP}
	 *                  to go one page up or
	 *                  {@link android.view.View#FOCUS_DOWN} to go one page down
	 * @return true if the key event is consumed by this method, false otherwise
	 */
	public boolean pageScroll(int direction) {
		boolean down = direction == View.FOCUS_DOWN;
		int height = getHeight();

		if (down) {
			mTempRect.top = getScrollY() + height;
			int count = getChildCount();
			if (count > 0) {
				View view = getChildAt(count - 1);
				if (mTempRect.top + height > view.getBottom()) {
					mTempRect.top = view.getBottom() - height;
				}
			}
		} else {
			mTempRect.top = getScrollY() - height;
			if (mTempRect.top < 0) {
				mTempRect.top = 0;
			}
		}
		mTempRect.bottom = mTempRect.top + height;

		return scrollAndFocus(direction, mTempRect.top, mTempRect.bottom);
	}

	/**
	 * <p>Handles scrolling in response to a "home/end" shortcut press. This
	 * method will scroll the view to the top or bottom and give the focus
	 * to the topmost/bottommost component in the new visible area. If no
	 * component is a good candidate for focus, this scrollview reclaims the
	 * focus.</p>
	 *
	 * @param direction the scroll direction: {@link android.view.View#FOCUS_UP}
	 *                  to go the top of the view or
	 *                  {@link android.view.View#FOCUS_DOWN} to go the bottom
	 * @return true if the key event is consumed by this method, false otherwise
	 */
	public boolean fullScroll(int direction) {
		boolean down = direction == View.FOCUS_DOWN;
		int height = getHeight();

		mTempRect.top = 0;
		mTempRect.bottom = height;

		if (down) {
			int count = getChildCount();
			if (count > 0) {
				View view = getChildAt(count - 1);
				mTempRect.bottom = view.getBottom() + getPaddingBottom();
				mTempRect.top = mTempRect.bottom - height;
			}
		}

		return scrollAndFocus(direction, mTempRect.top, mTempRect.bottom);
	}

	/**
	 * <p>Scrolls the view to make the area defined by <code>top</code> and
	 * <code>bottom</code> visible. This method attempts to give the focus
	 * to a component visible in this area. If no component can be focused in
	 * the new visible area, the focus is reclaimed by this ScrollView.</p>
	 *
	 * @param direction the scroll direction: {@link android.view.View#FOCUS_UP}
	 *                  to go upward, {@link android.view.View#FOCUS_DOWN} to downward
	 * @param top       the top offset of the new area to be made visible
	 * @param bottom    the bottom offset of the new area to be made visible
	 * @return true if the key event is consumed by this method, false otherwise
	 */
	private boolean scrollAndFocus(int direction, int top, int bottom) {
		boolean handled = true;

		int height = getHeight();
		int containerTop = getScrollY();
		int containerBottom = containerTop + height;
		boolean up = direction == View.FOCUS_UP;

		View newFocused = findFocusableViewInBounds(up, top, bottom);
		if (newFocused == null) {
			newFocused = this;
		}

		if (top >= containerTop && bottom <= containerBottom) {
			handled = false;
		} else {
			int delta = up ? (top - containerTop) : (bottom - containerBottom);
			doScrollY(delta);
		}

		if (newFocused != findFocus()) newFocused.requestFocus(direction);

		return handled;
	}

	/**
	 * Handle scrolling in response to an up or down arrow click.
	 *
	 * @param direction The direction corresponding to the arrow key that was
	 *                  pressed
	 * @return True if we consumed the event, false otherwise
	 */
	public boolean arrowScroll(int direction) {

		View currentFocused = findFocus();
		if (currentFocused == this) currentFocused = null;

		View nextFocused = FocusFinder.getInstance().findNextFocus(this, currentFocused, direction);

		final int maxJump = getMaxScrollAmount();

		if (nextFocused != null && isWithinDeltaOfScreen(nextFocused, maxJump, getHeight())) {
			nextFocused.getDrawingRect(mTempRect);
			offsetDescendantRectToMyCoords(nextFocused, mTempRect);
			int scrollDelta = computeScrollDeltaToGetChildRectOnScreen(mTempRect);
			doScrollY(scrollDelta);
			nextFocused.requestFocus(direction);
		} else {
			// no new focus
			int scrollDelta = maxJump;

			if (direction == View.FOCUS_UP && getScrollY() < scrollDelta) {
				scrollDelta = getScrollY();
			} else if (direction == View.FOCUS_DOWN) {
				if (getChildCount() > 0) {
					int daBottom = getChildAt(0).getBottom();
					int screenBottom = getScrollY() + getHeight() - getPaddingBottom();
					if (daBottom - screenBottom < maxJump) {
						scrollDelta = daBottom - screenBottom;
					}
				}
			}
			if (scrollDelta == 0) {
				return false;
			}
			doScrollY(direction == View.FOCUS_DOWN ? scrollDelta : -scrollDelta);
		}

		if (currentFocused != null && currentFocused.isFocused()
				&& isOffScreen(currentFocused)) {
			// previously focused item still has focus and is off screen, give
			// it up (take it back to ourselves)
			// (also, need to temporarily force FOCUS_BEFORE_DESCENDANTS so we are
			// sure to
			// get it)
			final int descendantFocusability = getDescendantFocusability();  // save
			setDescendantFocusability(ViewGroup.FOCUS_BEFORE_DESCENDANTS);
			requestFocus();
			setDescendantFocusability(descendantFocusability);  // restore
		}
		return true;
	}

	private boolean isOrthoMove(float moveX, float moveY) {
		return mHorizontal && Math.abs(moveY) > Math.abs(moveX)
				|| !mHorizontal && Math.abs(moveX) > Math.abs(moveY);
	}

	/**
	 * @return whether the descendant of this scroll view is scrolled off
	 *  screen.
	 */
	private boolean isOffScreen(View descendant) {
		if (mHorizontal) {
			return !isWithinDeltaOfScreen(descendant, getWidth(), 0);
		} else {
			return !isWithinDeltaOfScreen(descendant, 0, getHeight());
		}
	}

	/**
	 * @return whether the descendant of this scroll view is within delta
	 *  pixels of being on the screen.
	 */
	private boolean isWithinDeltaOfScreen(View descendant, int delta, int height) {
		descendant.getDrawingRect(mTempRect);
		offsetDescendantRectToMyCoords(descendant, mTempRect);
		if (mHorizontal) {
			return (mTempRect.right + delta) >= getScrollX()
					&& (mTempRect.left - delta) <= (getScrollX() + height);
		} else {
			return (mTempRect.bottom + delta) >= getScrollY()
					&& (mTempRect.top - delta) <= (getScrollY() + height);
		}
	}

	/**
	 * Smooth scroll by a Y delta
	 *
	 * @param delta the number of pixels to scroll by on the Y axis
	 */
	private void doScrollY(int delta) {
		if (delta != 0) {
			if (mSmoothScrollingEnabled) {
				if (mHorizontal) {
					smoothScrollBy(0, delta);
				} else {
					smoothScrollBy(delta, 0);
				}
			} else {
				if (mHorizontal) {
					scrollBy(0, delta);
				} else {
					scrollBy(delta, 0);
				}
			}
		}
	}

	/**
	 * Like {@link View#scrollBy}, but scroll smoothly instead of immediately.
	 *
	 * @param dx the number of pixels to scroll by on the X axis
	 * @param dy the number of pixels to scroll by on the Y axis
	 */
	public final void smoothScrollBy(int dx, int dy) {
		if (getChildCount() == 0) {
			// Nothing to do.
			return;
		}
		long duration = AnimationUtils.currentAnimationTimeMillis() - mLastScroll;
		if (duration > ANIMATED_SCROLL_GAP) {
			if (mHorizontal) {
				final int width = getWidth() - getPaddingRight() - getPaddingLeft();
				final int right = getChildAt(0).getWidth();
				final int maxX = Math.max(0, right - width);
				final int scrollX = getScrollX();
				dx = Math.max(0, Math.min(scrollX + dx, maxX)) - scrollX;
				mScroller.startScroll(scrollX, getScrollY(), dx, 0);
			} else {
				final int height = getHeight() - getPaddingBottom() - getPaddingTop();
				final int bottom = getChildAt(0).getHeight();
				final int maxY = Math.max(0, bottom - height);
				final int scrollY = getScrollY();
				dy = Math.max(0, Math.min(scrollY + dy, maxY)) - scrollY;
				mScroller.startScroll(getScrollX(), scrollY, 0, dy);
			}
			invalidate();
		} else {
			if (!mScroller.isFinished()) {
				mScroller.abortAnimation();
				if (mFlingStrictSpan != null) {
					mFlingStrictSpan.finish();
					mFlingStrictSpan = null;
				}
			}
			scrollBy(dx, dy);
		}
		mLastScroll = AnimationUtils.currentAnimationTimeMillis();
	}

	/**
	 * Like {@link #scrollTo}, but scroll smoothly instead of immediately.
	 *
	 * @param x the position where to scroll on the X axis
	 * @param y the position where to scroll on the Y axis
	 */
	public final void smoothScrollTo(int x, int y) {
		smoothScrollBy(x - getScrollX(), y - getScrollY());
	}

	/**
	 * <p>
	 * The scroll range of a scroll view is the overall height of all of its
	 * children.
	 * </p>
	 */
	@Override
	protected int computeVerticalScrollRange() {
		if (mHorizontal) {
			return super.computeVerticalScrollRange();
		}
		final int count = getChildCount();
		final int contentHeight = getHeight() - getPaddingBottom() - getPaddingTop();
		if (count == 0) {
			return contentHeight;
		}

		int scrollRange = getChildAt(0).getBottom();
		final int scrollY = getScrollY();
		final int overscrollBottom = Math.max(0, scrollRange - contentHeight);
		if (scrollY < 0) {
			scrollRange -= scrollY;
		} else if (scrollY > overscrollBottom) {
			scrollRange += scrollY - overscrollBottom;
		}

		return scrollRange;
	}

	/**
	 * <p>
	 * The scroll range of a scroll view is the overall height of all of its
	 * children.
	 * </p>
	 */
	@Override
	protected int computeHorizontalScrollRange() {
		if (!mHorizontal) {
			return super.computeHorizontalScrollRange();
		}
		final int count = getChildCount();
		final int contentWidth = getWidth() - getPaddingRight() - getPaddingLeft();
		if (count == 0) {
			return contentWidth;
		}

		int scrollRange = getChildAt(0).getRight();
		final int scrollX = getScrollX();
		final int overscrollBottom = Math.max(0, scrollRange - contentWidth);
		if (scrollX < 0) {
			scrollRange -= scrollX;
		} else if (scrollX > overscrollBottom) {
			scrollRange += scrollX - overscrollBottom;
		}

		return scrollRange;
	}

	@Override
	protected int computeVerticalScrollOffset() {
		return Math.max(0, super.computeVerticalScrollOffset());
	}

	@Override
	protected int computeHorizontalScrollOffset() {
		return Math.max(0, super.computeHorizontalScrollOffset());
	}

	@Override
	protected void measureChild(View child, int parentWidthMeasureSpec, int parentHeightMeasureSpec) {
		ViewGroup.LayoutParams lp = child.getLayoutParams();

		int childWidthMeasureSpec;
		int childHeightMeasureSpec;

		if (mHorizontal) {
			childHeightMeasureSpec = getChildMeasureSpec(parentHeightMeasureSpec, getPaddingTop()
					+ getPaddingBottom(), lp.height);

			childWidthMeasureSpec = MeasureSpec.makeMeasureSpec(0, MeasureSpec.UNSPECIFIED);
		} else {
			childWidthMeasureSpec = getChildMeasureSpec(parentWidthMeasureSpec, getPaddingLeft()
					+ getPaddingRight(), lp.width);

			childHeightMeasureSpec = MeasureSpec.makeMeasureSpec(0, MeasureSpec.UNSPECIFIED);
		}

		child.measure(childWidthMeasureSpec, childHeightMeasureSpec);
	}

	@Override
	protected void measureChildWithMargins(View child, int parentWidthMeasureSpec, int widthUsed,
			int parentHeightMeasureSpec, int heightUsed) {
		final MarginLayoutParams lp = (MarginLayoutParams) child.getLayoutParams();

		int childWidthMeasureSpec;
		int childHeightMeasureSpec;
		if (mHorizontal) {
			childHeightMeasureSpec = getChildMeasureSpec(parentHeightMeasureSpec,
					getPaddingTop() + getPaddingBottom() + lp.topMargin + lp.bottomMargin
					+ heightUsed, lp.height);
			childWidthMeasureSpec = MeasureSpec.makeMeasureSpec(
					lp.leftMargin + lp.rightMargin, MeasureSpec.UNSPECIFIED);
		} else {
			childWidthMeasureSpec = getChildMeasureSpec(parentWidthMeasureSpec,
					getPaddingLeft() + getPaddingRight() + lp.leftMargin + lp.rightMargin
					+ widthUsed, lp.width);
			childHeightMeasureSpec = MeasureSpec.makeMeasureSpec(
					lp.topMargin + lp.bottomMargin, MeasureSpec.UNSPECIFIED);
		}
		child.measure(childWidthMeasureSpec, childHeightMeasureSpec);
	}

	@Override
	public void computeScroll() {
		if (mScroller.computeScrollOffset()) {
			// This is called at drawing time by ViewGroup.  We don't want to
			// re-show the scrollbars at this point, which scrollTo will do,
			// so we replicate most of scrollTo here.
			//
			//         It's a little odd to call onScrollChanged from inside the drawing.
			//
			//         It is, except when you remember that computeScroll() is used to
			//         animate scrolling. So unless we want to defer the onScrollChanged()
			//         until the end of the animated scrolling, we don't really have a
			//         choice here.
			//
			//         I agree.  The alternative, which I think would be worse, is to post
			//         something and tell the subclasses later.  This is bad because there
			//         will be a window where mScrollX/Y is different from what the app
			//         thinks it is.
			//
			int oldX = getScrollX();
			int oldY = getScrollY();
			int x = mScroller.getCurrX();
			int y = mScroller.getCurrY();

			if (oldX != x || oldY != y) {
				if (mHorizontal) {
					overScrollBy(x - oldX, y - oldY, oldX, oldY, getScrollRange(), 0,
							mOverflingDistance, 0, false);
				} else {
					overScrollBy(x - oldX, y - oldY, oldX, oldY, 0, getScrollRange(),
							0, mOverflingDistance, false);
				}
				onScrollChanged(getScrollX(), getScrollY(), oldX, oldY);
			}
			awakenScrollBars();

			// Keep on drawing until the animation has finished.
			postInvalidate();
		} else {
			if (mFlingStrictSpan != null) {
				mFlingStrictSpan.finish();
				mFlingStrictSpan = null;
			}
		}
	}

	/**
	 * Scrolls the view to the given child.
	 *
	 * @param child the View to scroll to
	 */
	private void scrollToChild(View child) {
		child.getDrawingRect(mTempRect);

		/* Offset from child's local coordinates to ScrollView coordinates */
		offsetDescendantRectToMyCoords(child, mTempRect);
		scrollToChildRect(mTempRect, true);
	}

	/**
	 * If rect is off screen, scroll just enough to get it (or at least the
	 * first screen size chunk of it) on screen.
	 *
	 * @param rect      The rectangle.
	 * @param immediate True to scroll immediately without animation
	 * @return true if scrolling was performed
	 */
	private boolean scrollToChildRect(Rect rect, boolean immediate) {
		final int delta = computeScrollDeltaToGetChildRectOnScreen(rect);
		final boolean scroll = delta != 0;
		if (scroll) {
			if (immediate) {
				if (mHorizontal) {
					scrollBy(delta, 0);
				} else {
					scrollBy(0, delta);
				}
			} else {
				if (mHorizontal) {
					smoothScrollBy(delta, 0);
				} else {
					smoothScrollBy(0, delta);
				}
			}
		}
		return scroll;
	}

	/**
	 * Compute the amount to scroll in the Y direction in order to get
	 * a rectangle completely on the screen (or, if taller than the screen,
	 * at least the first screen size chunk of it).
	 *
	 * @param rect The rect.
	 * @return The scroll delta.
	 */
	protected int computeScrollDeltaToGetChildRectOnScreen(Rect rect) {
		if (mHorizontal) {
			return computeScrollDeltaToGetChildRectOnScreenHorizontal(rect);
		} else {
			return computeScrollDeltaToGetChildRectOnScreenVertical(rect);
		}
	}

	private int computeScrollDeltaToGetChildRectOnScreenVertical(Rect rect) {
		if (getChildCount() == 0) return 0;

		int height = getHeight();
		int screenTop = getScrollY();
		int screenBottom = screenTop + height;

		int fadingEdge = getVerticalFadingEdgeLength();

		// leave room for top fading edge as long as rect isn't at very top
		if (rect.top > 0) {
			screenTop += fadingEdge;
		}

		// leave room for bottom fading edge as long as rect isn't at very bottom
		if (rect.bottom < getChildAt(0).getHeight()) {
			screenBottom -= fadingEdge;
		}

		int scrollYDelta = 0;

		if (rect.bottom > screenBottom && rect.top > screenTop) {
			// need to move down to get it in view: move down just enough so
			// that the entire rectangle is in view (or at least the first
			// screen size chunk).

			if (rect.height() > height) {
				// just enough to get screen size chunk on
				scrollYDelta += (rect.top - screenTop);
			} else {
				// get entire rect at bottom of screen
				scrollYDelta += (rect.bottom - screenBottom);
			}

			// make sure we aren't scrolling beyond the end of our content
			int bottom = getChildAt(0).getBottom();
			int distanceToBottom = bottom - screenBottom;
			scrollYDelta = Math.min(scrollYDelta, distanceToBottom);

		} else if (rect.top < screenTop && rect.bottom < screenBottom) {
			// need to move up to get it in view: move up just enough so that
			// entire rectangle is in view (or at least the first screen
			// size chunk of it).

			if (rect.height() > height) {
				// screen size chunk
				scrollYDelta -= (screenBottom - rect.bottom);
			} else {
				// entire rect at top
				scrollYDelta -= (screenTop - rect.top);
			}

			// make sure we aren't scrolling any further than the top our content
			scrollYDelta = Math.max(scrollYDelta, -getScrollY());
		}
		return scrollYDelta;
	}

	private int computeScrollDeltaToGetChildRectOnScreenHorizontal(Rect rect) {
		if (getChildCount() == 0) return 0;

		int width = getWidth();
		int screenLeft = getScrollX();
		int screenRight = screenLeft + width;

		int fadingEdge = getHorizontalFadingEdgeLength();

		// leave room for left fading edge as long as rect isn't at very left
		if (rect.left > 0) {
			screenLeft += fadingEdge;
		}

		// leave room for right fading edge as long as rect isn't at very right
		if (rect.right < getChildAt(0).getWidth()) {
			screenRight -= fadingEdge;
		}

		int scrollXDelta = 0;

		if (rect.right > screenRight && rect.left > screenLeft) {
			// need to move right to get it in view: move right just enough so
			// that the entire rectangle is in view (or at least the first
			// screen size chunk).

			if (rect.width() > width) {
				// just enough to get screen size chunk on
				scrollXDelta += (rect.left - screenLeft);
			} else {
				// get entire rect at right of screen
				scrollXDelta += (rect.right - screenRight);
			}

			// make sure we aren't scrolling beyond the end of our content
			int right = getChildAt(0).getRight();
			int distanceToRight = right - screenRight;
			scrollXDelta = Math.min(scrollXDelta, distanceToRight);

		} else if (rect.left < screenLeft && rect.right < screenRight) {
			// need to move right to get it in view: move right just enough so that
			// entire rectangle is in view (or at least the first screen
			// size chunk of it).

			if (rect.width() > width) {
				// screen size chunk
				scrollXDelta -= (screenRight - rect.right);
			} else {
				// entire rect at left
				scrollXDelta -= (screenLeft - rect.left);
			}

			// make sure we aren't scrolling any further than the left our content
			scrollXDelta = Math.max(scrollXDelta, -getScrollX());
		}
		return scrollXDelta;
	}


	@Override
	public void requestChildFocus(View child, View focused) {
		if (!mIsLayoutDirty) {
			scrollToChild(focused);
		} else {
			// The child may not be laid out yet, we can't compute the scroll yet
			mChildToScrollTo = focused;
		}
		super.requestChildFocus(child, focused);
	}


	/**
	 * When looking for focus in children of a scroll view, need to be a little
	 * more careful not to give focus to something that is scrolled off screen.
	 *
	 * This is more expensive than the default {@link android.view.ViewGroup}
	 * implementation, otherwise this behavior might have been made the default.
	 */
	@Override
	protected boolean onRequestFocusInDescendants(int direction,
			Rect previouslyFocusedRect) {

		// convert from forward / backward notation to up / down / left / right
		// (ugh).
		if (mHorizontal) {
			if (direction == View.FOCUS_FORWARD) {
				direction = View.FOCUS_RIGHT;
			} else if (direction == View.FOCUS_BACKWARD) {
				direction = View.FOCUS_LEFT;
			}
		} else {
			if (direction == View.FOCUS_FORWARD) {
				direction = View.FOCUS_DOWN;
			} else if (direction == View.FOCUS_BACKWARD) {
				direction = View.FOCUS_UP;
			}
		}

		final View nextFocus = previouslyFocusedRect == null ?
				FocusFinder.getInstance().findNextFocus(this, null, direction) :
					FocusFinder.getInstance().findNextFocusFromRect(this,
							previouslyFocusedRect, direction);

				if (nextFocus == null) {
					return false;
				}

				if (isOffScreen(nextFocus)) {
					return false;
				}

				return nextFocus.requestFocus(direction, previouslyFocusedRect);
	}

	@Override
	public boolean requestChildRectangleOnScreen(View child, Rect rectangle,
			boolean immediate) {
		// offset into coordinate space of this scroll view
		rectangle.offset(child.getLeft() - child.getScrollX(),
				child.getTop() - child.getScrollY());

		return scrollToChildRect(rectangle, immediate);
	}

	@Override
	public void requestLayout() {
		mIsLayoutDirty = true;
		super.requestLayout();
	}

	@Override
	protected void onDetachedFromWindow() {
		super.onDetachedFromWindow();

		if (mScrollStrictSpan != null) {
			mScrollStrictSpan.finish();
			mScrollStrictSpan = null;
		}
		if (mFlingStrictSpan != null) {
			mFlingStrictSpan.finish();
			mFlingStrictSpan = null;
		}
	}

	@Override
	protected void onLayout(boolean changed, int l, int t, int r, int b) {
		super.onLayout(changed, l, t, r, b);
		mIsLayoutDirty = false;
		// Give a child focus if it needs it
		if (mChildToScrollTo != null && isViewDescendantOf(mChildToScrollTo, this)) {
			scrollToChild(mChildToScrollTo);
		}
		mChildToScrollTo = null;

		// Calling this with the present values causes it to re-clam them
		scrollTo(getScrollX(), getScrollY());
	}

	@Override
	protected void onSizeChanged(int w, int h, int oldw, int oldh) {
		super.onSizeChanged(w, h, oldw, oldh);

		View currentFocused = findFocus();
		if (null == currentFocused || this == currentFocused)
			return;

		// If the currently-focused view was visible on the screen when the
		// screen was at the old height, then scroll the screen to make that
		// view visible with the new screen height.
		if (isWithinDeltaOfScreen(currentFocused, 0, oldh)) {
			currentFocused.getDrawingRect(mTempRect);
			offsetDescendantRectToMyCoords(currentFocused, mTempRect);
			int scrollDelta = computeScrollDeltaToGetChildRectOnScreen(mTempRect);
			doScrollY(scrollDelta);
		}
	}

	/**
	 * Return true if child is an descendant of parent, (or equal to the parent).
	 */
	private boolean isViewDescendantOf(View child, View parent) {
		if (child == parent) {
			return true;
		}

		final ViewParent theParent = child.getParent();
		return (theParent instanceof ViewGroup) && isViewDescendantOf((View) theParent, parent);
	}

	/**
	 * Fling the scroll view
	 *
	 * @param velocityY The initial velocity in the Y direction. Positive
	 *                  numbers mean that the finger/cursor is moving down the screen,
	 *                  which means we want to scroll towards the top.
	 */
	public void fling(int velocityY) {
		if (getChildCount() > 0) {
			if (mHorizontal) {
				int width = getWidth() - getPaddingRight() - getPaddingLeft();
				int right = getChildAt(0).getWidth();

				mScroller.fling(getScrollX(), getScrollY(), velocityY, 0,
						0, Math.max(0, right - width), 0, 0, width/2, 0);
			} else {
				int height = getHeight() - getPaddingBottom() - getPaddingTop();
				int bottom = getChildAt(0).getHeight();

				mScroller.fling(getScrollX(), getScrollY(), 0, velocityY, 0, 0, 0,
						Math.max(0, bottom - height), 0, height/2);
			}
			if (mFlingStrictSpan == null) {
				mFlingStrictSpan = enterCriticalSpan("ScrollView-fling");
			}

			invalidate();
		}
	}

	private void endDrag() {
		mIsBeingDragged = false;
		mIsOrthoDragged = false;
		mDownView = null;
		recycleVelocityTracker();
		if (mScrollStrictSpan != null) {
			mScrollStrictSpan.finish();
			mScrollStrictSpan = null;
		}
	}

	private void invalidateParentIfNeeded() {
		if (isHardwareAccelerated() && getParent() instanceof View) {
			((View) getParent()).invalidate();
		}
	}

	/**
	 * {@inheritDoc}
	 *
	 * <p>This version also clamps the scrolling to the bounds of our child.
	 */
	@Override
	public void scrollTo(int x, int y) {
		// we rely on the fact the View.scrollBy calls scrollTo.
		if (getChildCount() > 0) {
			View child = getChildAt(0);
			x = clamp(x, getWidth() - getPaddingRight() - getPaddingLeft(), child.getWidth());
			y = clamp(y, getHeight() - getPaddingBottom() - getPaddingTop(), child.getHeight());
			if (x != getScrollX() || y != getScrollY()) {
				super.scrollTo(x, y);
			}
		}
	}

	private int clamp(int n, int my, int child) {
		if (my >= child || n < 0) {
			/* my >= child is this case:
			 *                    |--------------- me ---------------|
			 *     |------ child ------|
			 * or
			 *     |--------------- me ---------------|
			 *            |------ child ------|
			 * or
			 *     |--------------- me ---------------|
			 *                                  |------ child ------|
			 *
			 * n < 0 is this case:
			 *     |------ me ------|
			 *                    |-------- child --------|
			 *     |-- mScrollX --|
			 */
			return 0;
		}
		if ((my+n) > child) {
			/* this case:
			 *                    |------ me ------|
			 *     |------ child ------|
			 *     |-- mScrollX --|
			 */
			return child-my;
		}
		return n;
	}

	private static class Span {
		private String mName;
		private Span mNext;
		private Span mPrev;  // not used when in freeList, only active
		private final ThreadSpanState mContainerState;

		Span(ThreadSpanState threadState) {
			mContainerState = threadState;
		}

		public void finish() {

			ThreadSpanState state = mContainerState;

			synchronized (state) {
				if (mName == null) {
					// Duplicate finish call.  Ignore.
					return;
				}

				// Remove ourselves from the active list.
				if (mPrev != null) {
					mPrev.mNext = mNext;
				}

				if (mNext != null) {
					mNext.mPrev = mPrev;
				}

				if (state.mActiveHead == this) {
					state.mActiveHead = mNext;
				}

				this.mName = null;
				this.mPrev = null;
				this.mNext = null;

				// Add ourselves to the freeList, if it's not already
				// too big.
				if (state.mFreeListSize < 5) {
					this.mNext = state.mFreeListHead;
					state.mFreeListHead = this;
					state.mFreeListSize++;
				}
			}
		}
	}

	private static class ThreadSpanState {
		public Span mActiveHead;    // doubly-linked list.
		public Span mFreeListHead;  // singly-linked list.  only changes at head.
		public int mFreeListSize;
	}

	private static Span enterCriticalSpan(String name) {    	
		if (name == null || name.isEmpty()) {
			throw new IllegalArgumentException("name must be non-null and non-empty");
		}
		ThreadSpanState state = sThisThreadSpanState.get();

		Span span = null;

		synchronized (state) {
			if (state.mFreeListHead != null) {
				span = state.mFreeListHead;
				state.mFreeListHead = span.mNext;
				state.mFreeListSize--;
			} else {
				// Shouldn't have to do this often.
				span = new Span(state);
			}

			span.mName = name;
			span.mNext = state.mActiveHead;
			span.mPrev = null;
			state.mActiveHead = span;

			if (span.mNext != null) {
				span.mNext.mPrev = span;
			}
		}

		return span;
	}

	private static final ThreadLocal<ThreadSpanState> sThisThreadSpanState = new ThreadLocal<ThreadSpanState>() {
		@Override
		protected ThreadSpanState initialValue() {
			return new ThreadSpanState();
		}
	};

}
